Conventionally, in a punch press such as a turret punch press, a technique of performing burring process or drilling process to a plate-like work and then performing tapping process to the part subjected to burring process or a prepared hole has been disclosed. The technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 8-71848 (hereinafter referred to as “patent document 1”) and Japanese Patent Application Laid-Open No. 9-155638 (hereinafter referred to as “patent document 2”).
Further, the configuration in which tapping process is performed by attaching a tapping device to a rotating mold indexing device rotatably provided at the punch press has been developed. It is disclosed in, for example, Japanese Utility Model Registration Publication No. 2541404 (hereinafter referred to as “patent document 3”) and Japanese Patent Application Laid-Open No. 7-185975 (hereinafter referred to as “patent document 4”).
On the other hand, in a conventional tapping device, as a configuration of detecting whether or not a tap is broken, the configuration in which an operator activated by the tap passing through a work is provided at a tap die supporting the work in opposed to the tap and breakage of the tap is detected by detecting that this operator has been activated by a sensor such as a micro switch has been developed. It is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-47197 (hereinafter referred to as “patent document 5”).
According the invention described in the patent document 1, it is the configuration in which linear motion when a head member in a rotational tool device with a rotational tool such as tap and reamer is pressed and lowered by a vertically-movable ram (striker) provided at the punch press is converted into rotational motion, thereby to rotate the rotational tool.
The above-mentioned configuration has the following problems: conversion of linear motion into rotational motion makes the configuration complicated and a short length of vertical stroke of the ram requires increasing the number of the rotational tool, resulting in short lifetime of the tap.
According the invention described in the patent document 2, since a process position by the punch press greatly deviates from a tapping process position by the tapping device, when a prepared hole is processed in the vicinity of the end part of the work for tapping process, a work holding position by a work positioning device for positioning transfer position of the work needs to be changed and a motor for driving the tapping device or the like needs to be provided separately.
Accordingly, to improve processing efficiency and simplify the configuration, further improvement is desired.
According the invention described in the patent document 3, since the tapping tool is attached to the rotating mold indexing device provided at the punch press and the tapping tool is rotated by using the motor of the rotating mold indexing device, the above-mentioned problems in the cited references 1 and 2 can be solved. However, in this configuration, the tap is fed by providing a master screw and rotating speed of the tap is increased by using a planetary gear drive or the like, leading to the problem that the whole configuration becomes complicated.
According the invention described in the patent document 4, since the tapping tool is attached to the rotating mold indexing device provided at the punch press and the tap is rotated by using the motor of the rotating mold indexing device to perform tapping process, a head part has an engaging part with the ram and a speed increasing mechanism for increasing the rotational speed of the tap in the state where the ram is engaged with the engaging part is provided, resulting in more complicated configuration.
Further, in the patent document 5, by turning ON or OFF the micro switch as a sensor by operation of the operator provided at the tap die, breakage of the tap is detected and when the micro switch breaks down in the ON or OFF state, it is difficult to determine whether the ON or OFF state is caused by failure of the breakage of the tap or the micro switch.
In the patent document 5, there is a problem that the operator provided at the tap die is an obstacle when discharging chips generated during tapping process.
To solve the above-mentioned problems, a first object of the present invention is to provide a tapping method, a tapping device and a punch press which can readily perform tapping process by using the rotating mold indexing device provided at the punch press with simple configuration.
A second object of the present invention is to provide a tapping method, a tapping device and a punch press which can detect breakage of the tap and failure of the sensor for detecting the breakage.
Further, a third object of the present invention is to provide a tapping method, a tapping device and a punch press which can suck and discharge chips generated during tapping process.